Abstract
Impact loads initiate damages of several forms such as an indentation, fiber breakage, matrix cracking, and delamination cracking in carbon fiber reinforced polymer (CFRP). In this study, rapid diagnosis, which can finish inspecting the whole aircraft structure within an hour during refueling, was developed for composite aircraft. The proposed method consists of two steps; the first target for detection is indentation in the whole structure, and the second one is delamination cracking. After an indentation is detected in the first step, you only have to inspect limited area around the indentation for delamination inspection. Therefore, you can make use of an indentation as a marker of impact damage and can save inspection time and money even if large CFRP components are inspected. In the first step for indentation detection, indentation increases fiber-fiber contact at the interlaminar interface and electrical conductivity. Consequently, electrical current applied to the material will concentrate around the indentation, and lead to selective and intense resistive heating. This temperature increase can be observed by thermography or detected as a change in electrical resistance caused by the temperature difference. In the second step, delamination around an indentation can be detected without sampling the data from intact structures using statistical treatment. Moreover false diagnoses from changes in resistance caused by damage to the electrical contacts at the electrodes can be prevented.
